
#pragma once

namespace SipHashOrg
{
    /*
    SipHash reference C implementation

    Written in 2012 by
    Jean-Philippe Aumasson <jeanphilippe.aumasson@gmail.com>
    Daniel J. Bernstein <djb@cr.yp.to>

    To the extent possible under law, the author(s) have dedicated all copyright
    and related and neighboring rights to this software to the public domain
    worldwide. This software is distributed without any warranty.

    You should have received a copy of the CC0 Public Domain Dedication along with
    this software. If not, see <http://creativecommons.org/publicdomain/zero/1.0/>.
    */

    typedef unsigned long long u64;
    typedef unsigned int u32;
    typedef unsigned char u8;

    #define ROTL(x,b) (u64)( ((x) << (b)) | ( (x) >> (64 - (b))) )

    #define U32TO8_LE(p, v)                                    \
        (p)[0] = (u8)((v)); (p)[1] = (u8)((v) >> 8);           \
        (p)[2] = (u8)((v) >> 16); (p)[3] = (u8)((v) >> 24);

    #define U64TO8_LE(p, v)                 \
        U32TO8_LE((p), (u32)((v)));         \
        U32TO8_LE((p)+4, (u32)((v) >> 32));

    #define U8TO64_LE(p)        \
        (((u64)((p)[0])) |      \
        ((u64)((p)[1]) << 8) |  \
        ((u64)((p)[2]) << 16) | \
        ((u64)((p)[3]) << 24) | \
        ((u64)((p)[4]) << 32) | \
        ((u64)((p)[5]) << 40) | \
        ((u64)((p)[6]) << 48) | \
        ((u64)((p)[7]) << 56))

    #define SIPROUND                                              \
        v0 += v1; v1 = ROTL(v1, 13); v1 ^= v0; v0 = ROTL(v0, 32); \
        v2 += v3; v3 = ROTL(v3, 16); v3 ^= v2;                    \
        v0 += v3; v3 = ROTL(v3, 21); v3 ^= v0;                    \
        v2 += v1; v1 = ROTL(v1, 17); v1 ^= v2; v2 = ROTL(v2, 32);

    /* SipHash-2-4 */
    void crypto_auth(unsigned char *out, const unsigned char *in, unsigned long long inlen, const unsigned char *k)
    {
        /* "somepseudorandomlygeneratedbytes" */
        u64 v0 = 0x736f6d6570736575ULL;
        u64 v1 = 0x646f72616e646f6dULL;
        u64 v2 = 0x6c7967656e657261ULL;
        u64 v3 = 0x7465646279746573ULL;
        u64 b;
        u64 k0 = U8TO64_LE(k);
        u64 k1 = U8TO64_LE(k + 8);
        u64 m;
        const u8 *end = in + inlen - (inlen % sizeof(u64));
        const int left = inlen & 7;
        b = ((u64)inlen) << 56;
        v3 ^= k1;
        v2 ^= k0;
        v1 ^= k1;
        v0 ^= k0;

        for (; in != end; in += 8)
        {
            m = U8TO64_LE(in);
            //#ifdef DEBUG
            //            printf("(%3d) v0 %08x %08x\n", (int)inlen, (u32)(v0 >> 32), (u32)v0);
            //            printf("(%3d) v1 %08x %08x\n", (int)inlen, (u32)(v1 >> 32), (u32)v1);
            //            printf("(%3d) v2 %08x %08x\n", (int)inlen, (u32)(v2 >> 32), (u32)v2);
            //            printf("(%3d) v3 %08x %08x\n", (int)inlen, (u32)(v3 >> 32), (u32)v3);
            //            printf("(%3d) compress %08x %08x\n", (int)inlen, (u32)(m >> 32), (u32)m);
            //#endif
            v3 ^= m;
            SIPROUND;
            SIPROUND;
            v0 ^= m;
        }

        switch (left)
        {
            case 7: b |= ((u64)in[6]) << 48;

            case 6: b |= ((u64)in[5]) << 40;

            case 5: b |= ((u64)in[4]) << 32;

            case 4: b |= ((u64)in[3]) << 24;

            case 3: b |= ((u64)in[2]) << 16;

            case 2: b |= ((u64)in[1]) << 8;

            case 1: b |= ((u64)in[0]); break;

            case 0: break;
        }

        //#ifdef DEBUG
        //        printf("(%3d) v0 %08x %08x\n", (int)inlen, (u32)(v0 >> 32), (u32)v0);
        //        printf("(%3d) v1 %08x %08x\n", (int)inlen, (u32)(v1 >> 32), (u32)v1);
        //        printf("(%3d) v2 %08x %08x\n", (int)inlen, (u32)(v2 >> 32), (u32)v2);
        //        printf("(%3d) v3 %08x %08x\n", (int)inlen, (u32)(v3 >> 32), (u32)v3);
        //        printf("(%3d) padding   %08x %08x\n", (int)inlen, (u32)(b >> 32), (u32)b);
        //#endif
        v3 ^= b;
        SIPROUND;
        SIPROUND;
        v0 ^= b;
        //#ifdef DEBUG
        //        printf("(%3d) v0 %08x %08x\n", (int)inlen, (u32)(v0 >> 32), (u32)v0);
        //        printf("(%3d) v1 %08x %08x\n", (int)inlen, (u32)(v1 >> 32), (u32)v1);
        //        printf("(%3d) v2 %08x %08x\n", (int)inlen, (u32)(v2 >> 32), (u32)v2);
        //        printf("(%3d) v3 %08x %08x\n", (int)inlen, (u32)(v3 >> 32), (u32)v3);
        //#endif
        v2 ^= 0xff;
        SIPROUND;
        SIPROUND;
        SIPROUND;
        SIPROUND;
        b = v0 ^ v1 ^ v2  ^ v3;
        U64TO8_LE(out, b);
    }
}